Field of the Invention
The present invention relates to an image forming apparatus such as electrophotographic printing apparatus, and more particularly to an image forming unit incorporated in the image forming apparatus.
Description of the Related Art
An electrophotographic process is used in conventional image forming apparatus including electrophotographic printers, copying machines, and facsimile machines. The surface of a photoconductive body is uniformly charged. The charged surface is irradiated with light in accordance with print data to form an electrostatic latent image. Toner is supplied to the electrostatic latent image to develop the electrostatic latent image into a toner image. The toner image is then transferred onto paper. The toner image on the paper is then fixed into a permanent image under heat and pressure.
Japanese Patent Application Laid-Open No. 2007-101718 (see Page 6, FIG. 4) discloses one such image forming apparatus. A conventional image forming apparatus includes a toner cartridge that holds toner therein, and a developing unit that supplies the toner to an electrostatic latent image formed on a photoconductive body to develop the electrostatic latent image into a toner image. The toner cartridge and developing unit have openings, respectively. The toner is supplied through the openings from the toner cartridge into the developing unit.
A toner transporting means is located under the opening of the developing unit. The toner transporting means includes a toner guide that guides the toner and a transporting spiral that transports the toner along the toner guide in opposite directions with respect to the receiving opening, so that a fraction of the toner falls into the developing unit as the toner is advanced along the toner guide. As a result, the toner is distributed in the developing unit substantially uniformly along the toner guide.
The above-described toner transporting means suffers from a problem in that the toner in the vicinity of the openings may agglomerate, being an obstacle to smooth supply of toner from the toner cartridge in to the developing unit.